The objectives of the proposed study are to 1) conduct a series of cost-effectiveness analyses of interventions being delivered in a currently funded NIDA study entitled "Reducing Barriers to Drug Abuse Treatment Services" (Harvey Siegal, PhD, PI, R01 DA015690-01), 2) determine the sensitivity of two general effectiveness measures to substance abuse outcomes, and 3) determine predictors for these general effectiveness measures in a substance abuse treatment-seeking sample. The currently funded parent study randomly assigns subjects to one of two possible interventions or usual care. The intervention conditions are a motivational interviewing intervention and a strengths-based case management intervention. The goals of the interventions are to facilitate substance abuse treatment linkage and treatment engagement. The parent study was not funded to conduct cost-effectiveness analyses. The proposed study is requesting additional cost and effectiveness data in order to conduct the economic and methodologic analyses. Costs will be estimated with the Brief Drug Abuse Treatment Cost Analysis Program (Brief DATCAP) and the Client DATCAP. Effectiveness will be measured using disease-specific and general effectiveness measures. The disease-specific effectiveness measures will include treatment linkage, treatment engagement, abstinence, and early remission of substance dependence. The general effectiveness measure will include changes in patient well being, as defined by quality-adjusted life years (QALYs). Cost data will be collected at baseline, 3-, and 6-months. Effectiveness data will be collected at baseline and 6-months. Cost-effectiveness ratios will be calculated using bootstrap with replacement re-sampling methods. To date, cost per QALY analyses have not been done for substance abuse interventions. Cost per QALY analyses will provide an additional metric for communicating the value of substance abuse interventions and will allow for direct comparison with existing cost per QALY ratios for other mental and physical health interventions.